U.S. Pat. No. 3,915,921 discloses copolymers of unsaturated carboxylic acid monomers with an alkyl acrylate ester wherein the alkyl group contains about 10 to 30 carbon atoms that are efficient water thickeners, which when neutralized by basic materials have improved resistance to loss in viscosity, even in the presence of substantial amounts of inorganic salts such as sodium chloride. These copolymers absorb water, but copolymers having improved rates of water absorption and retention are desired.